A Case Study of Crop Model Applications in An Increasing Diversity of Genetically Modified Traits

A study was conducted to develop variety files for six GM cultivars. Several experiments were conducted between 2001 and 2006 by varying cultivars, nitrogen, irrigation and PIX applications on two different soils in two different growing seasons.  In each experiment, plant height and numbers of main stem nodes, squares, bolls and biomass of various parts of plant were measured several times during the growing season. Lint yield was measured at the end of each experiment. The cotton model, GOSSYM, was used to simulate the growth, development and yield of six GM cultivars across years and management practices. We found that 25 cultivar parameters of variety file that included phenology, growth, and partitioning coefficients, are needed to be changed to simulate the GM cultivars. Graphical and statistical methods were used to test the predictive capacity of the model for GM cultivars. The simulated growth, phenology, and yield data are very close with observed data showing the robustness of the functions used in the model. The correlation coefficients between observed and simulated yields for all varieties ranged between 0.56 and 0.87. This study also proves that the validated cotton simulation model with GM cultivar variety files will be immensely beneficial to several federal and state agencies and consultants who are currently using the GOSSYM cotton model for natural resource management.